/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 */

package com.zhs.gccs.utils.zip.extra;

import static com.zhs.gccs.utils.zip.extra.ZipConstants.BYTE_MASK;
import static com.zhs.gccs.utils.zip.extra.ZipConstants.WORD;

/**
 * This is a class that has been made significantly smaller (deleted a bunch of
 * methods) and originally is from the Apache Ant Project
 * (http://ant.apache.org), org.apache.tools.zip package. All license and other
 * documentation is intact.
 * 
 * Utility class that represents a four byte integer with conversion rules for
 * the big endian byte order of ZIP files.
 * 
 */
public final class ZipLong implements Cloneable {

	// private static final int BYTE_BIT_SIZE = 8;

	private static final int BYTE_1 = 1;
	private static final int BYTE_1_MASK = 0xFF00;
	private static final int BYTE_1_SHIFT = 8;

	private static final int BYTE_2 = 2;
	private static final int BYTE_2_MASK = 0xFF0000;
	private static final int BYTE_2_SHIFT = 16;

	private static final int BYTE_3 = 3;
	private static final long BYTE_3_MASK = 0xFF000000L;
	private static final int BYTE_3_SHIFT = 24;

	private final long value;

	/** Central File Header Signature */
	public static final ZipLong CFH_SIG = new ZipLong(0X02014B50L);

	/** Local File Header Signature */
	public static final ZipLong LFH_SIG = new ZipLong(0X04034B50L);

	/**
	 * Data Descriptor signature
	 */
	public static final ZipLong DD_SIG = new ZipLong(0X08074B50L);

	/**
	 * Value stored in size and similar fields if ZIP64 extensions are used.
	 */
	static final ZipLong ZIP64_MAGIC = new ZipLong(ZipConstants.ZIP64_MAGIC);

	/**
	 * Create instance from a number.
	 * 
	 * @param value
	 *            the long to store as a ZipLong
	 * @since 1.1
	 */
	public ZipLong(long value) {
		this.value = value;
	}

	/**
	 * Create instance from bytes.
	 * 
	 * @param bytes
	 *            the bytes to store as a ZipLong
	 * @since 1.1
	 */
	public ZipLong(byte[] bytes) {
		this(bytes, 0);
	}

	/**
	 * Create instance from the four bytes starting at offset.
	 * 
	 * @param bytes
	 *            the bytes to store as a ZipLong
	 * @param offset
	 *            the offset to start
	 * @since 1.1
	 */
	public ZipLong(byte[] bytes, int offset) {
		value = ZipLong.getValue(bytes, offset);
	}

	/**
	 * Get value as four bytes in big endian byte order.
	 * 
	 * @since 1.1
	 * @return value as four bytes in big endian order
	 */
	public byte[] getBytes() {
		return ZipLong.getBytes(value);
	}

	/**
	 * Get value as Java long.
	 * 
	 * @since 1.1
	 * @return value as a long
	 */
	public long getValue() {
		return value;
	}

	/**
	 * Get value as four bytes in big endian byte order.
	 * 
	 * @param value
	 *            the value to convert
	 * @return value as four bytes in big endian byte order
	 */
	public static byte[] getBytes(long value) {
		byte[] result = new byte[WORD];
		result[0] = (byte) ((value & BYTE_MASK));
		result[BYTE_1] = (byte) ((value & BYTE_1_MASK) >> BYTE_1_SHIFT);
		result[BYTE_2] = (byte) ((value & BYTE_2_MASK) >> BYTE_2_SHIFT);
		result[BYTE_3] = (byte) ((value & BYTE_3_MASK) >> BYTE_3_SHIFT);
		return result;
	}

	/**
	 * Helper method to get the value as a Java long from four bytes starting at
	 * given array offset
	 * 
	 * @param bytes
	 *            the array of bytes
	 * @param offset
	 *            the offset to start
	 * @return the corresponding Java long value
	 */
	public static long getValue(byte[] bytes, int offset) {
		long value = (bytes[offset + BYTE_3] << BYTE_3_SHIFT) & BYTE_3_MASK;
		value += (bytes[offset + BYTE_2] << BYTE_2_SHIFT) & BYTE_2_MASK;
		value += (bytes[offset + BYTE_1] << BYTE_1_SHIFT) & BYTE_1_MASK;
		value += (bytes[offset] & BYTE_MASK);
		return value;
	}

	/**
	 * Helper method to get the value as a Java long from a four-byte array
	 * 
	 * @param bytes
	 *            the array of bytes
	 * @return the corresponding Java long value
	 */
	public static long getValue(byte[] bytes) {
		return getValue(bytes, 0);
	}

	/**
	 * Override to make two instances with same value equal.
	 * 
	 * @param o
	 *            an object to compare
	 * @return true if the objects are equal
	 * @since 1.1
	 */
	@Override
	public boolean equals(Object o) {
		if (o == null || !(o instanceof ZipLong)) {
			return false;
		}
		return value == ((ZipLong) o).getValue();
	}

	/**
	 * Override to make two instances with same value equal.
	 * 
	 * @return the value stored in the ZipLong
	 * @since 1.1
	 */
	@Override
	public int hashCode() {
		return (int) value;
	}

	@Override
	public Object clone() {
		try {
			return super.clone();
		}
		catch (CloneNotSupportedException cnfe) {
			// impossible
			throw new RuntimeException(cnfe);
		}
	}

	@Override
	public String toString() {
		return "ZipLong value: " + value;
	}
}
